Sunday, November 4, 2012

Avoid Desiccated thyroid hormone replacement is still a good idea

I am repeating this post from almost 1 year ago because it continues to get  comments with varying opinions  from my readers. Please review this including the comments  below. I have
also attached 2 articles discussing the small percentage of people who do have a genetically caused problem with an enzyme system that reduces T3, the active form of thyroid hormone .

Have fun , Be smart  study any health problem you may have . Having an informed discussion with your doctor may improve your overall health.
David Calder,MD

Avoid Desiccated Thyroid Hormone Replacement

Avoid Desiccated Thyroid Hormone Replacement

Desiccated thyroid hormone , Armour thyroid and Thyroid USP is listed as obsolete by the FDA but continues to be prescribed and used by some people . I recently saw a video promoting the use of desiccated thyroid which prompted me to write this note.

Our thyroid gland produces thyroid hormone in a response to TSH ( thyroid stimulating hormone ) from our pituitary gland. The primary form of thyroid hormone produced and released into our blood is T4 . This T4 is slowly converted to the active hormone T3 in our tissues,primarily the liver . The T3 Hormone in correct amounts helps keep all of the cells of our body running at peak efficiency.

A deficiency of T4 and T3 results in a slow down of all of the machinery in our body and an excess of T4 and T3 can have toxic effects especially for our heart causing arrhythmia , heart failure , angina or even cardiac arrest. The effect of excess T3 is a concern for anyone with heart disease.
( many of us have a little silent coronary heart disease ).

So, why is desiccated thyroid hormone not a recommended treatment for hypothyroidism ?

Desiccated Thyroid Hormone is of animal thyroid tissue origin. This means that it contains a mixture of T4 and T3. The T3 is almost 100% absorbed rapidly producing abnormally high levels of T3 in the blood stream and potentially a toxic effect on that persons heart.

Levothyroxine ( L-thyroxine , levothyroid , synthyroid and others) is T4 and is much safer to use. The T4 is absorbed and converted slowly to the active T3 , similar to the function of a normal thyroid gland. Be safe . If you need thyroid hormone replacement, use T4.
Dr. Calder


  1. Hey very interesting blog!
    Look into my page : Adrenal Fatigue Mild anxiety
  2. This doctor or whatever he is...doesn't know what he's talking about. Most who suffer from hypothyroidism have found that T4 only treatment is horrible and that we DO NOT convert T4 to T3 readily. It has also been proven that taking NDT (Natural Desiccated Thyroid) helps prevent heart problems and heart attacks. Do the research Dr. Calder. I tried T4 only treatment and still felt like crap. Adding T3 into my regime only made things worse. It wasn't until I started taking NDT that I got optimized and all my hypo symptoms went away. Try looking up Janie Alexander Bowthorpe's STTM page on Facebook. 7000 of us strong and 90% of those on this board take NDT and have found it far superior to T4 only treatment. You are just like the 5 or 6 Endo's that I have fired who told me..."here take this one little pill (T4) and it will make you feel all better. To that I say BS! T4 does nothing but make most people sicker. Adding in T3 helps...but it is NDT that really makes the difference
  3. Thanks for your comment. We are fortunate to have a variety of options available to help manage the various medical problems we all deal with in our lives. It is good that you found something that works for you. Dr. Calder
  4. Hi, it seems to be very complex. I think a lot of people who are hypothyroid, most of whom have autoimmune disease, do not respond well to T4 alone. I appreciate you bringing up concern about risks, but going untreated or unsuccessfully treating with T4 is also risking heart problems. Not to mention many untreated or T4-supplemented patients whose lives have come to a standstill because of extreme fatigue, memory problems, and mood swings. So treating immune and adrenal imbalance and its possible causes with diet and safe herbs and supplements, and if necessary proceeding cautiously with whatever form of thyroid hormone works to improve life in general, seems imperative.
  5. I have hashi and 2 months ago tried a combination of t4/t3 at 76mcg/18mcg split. I am 34, super fit and I recently took a ride in the back of an ambulance twice for cardiac arrythmia!!!! It was very, very scary. Today I skipped my dose and my resting heart rate immediately returned to normal at 60bpm versus the last two months of 80-90. We are all different but I think it's disrespectful and wrong to say the doc doesn't know of what he speaks. I also tried dedicated and my hr went the other way to 42bpm. So, guess who is going back to t4 only? Me. Thanks doc- this is important information.
  6. also the chinese have been using desiccated for 2100 years yes that's 900BC so I am going to buy it off the net instead of t4/t3 which is all we get in the uk as it's CHEAP! crap life for thirty years, don't forget desiccated adrenal which so farr is saving my life.
  7. Thanks for your comment.
    I would use caution in buying any medication from the internet, especially desiccated thyroid. You have no idea of where or under what conditions the internet medications are produced.( see my post above)
    Treating the lab test TSH , free T4 is easier than treating the symptoms of hypothyroidism . The symptoms of tiredness and fatique may have other causes. Many people with hypothyroidism have Hashimotos Thyroiditis ( a chronic autoimmune inflammation of the thyroid gland) causing the symptoms .
    T3,has 3 iodine molecules,and is the active form of Thyroid hormone . It is produced in our body by by an enzyme that removes one iodine molecule from T4 . T4 has 4 iodine molecules and is the less active precursor to T3. A small percentage of people with Hypothyroidism may also have genetically cause malfunction of the enzyme system responsible for removing an iodine molecule from T4 resulting in a deficiency of
    T3. This person will benefit from taking a thyroid replacement containing both T4 and T3.

    I recommend seeing an endocrinologist for an opinion and using FDA approved thyroid from your local pharmacy and avoiding desiccated thyroid.
    Dr. Calder
    The attached articles that may add to your understanding of some of the problems of thyroid hormone replacement.
    Dr. Calder
    J Clin Endocrinol Metab. 2009 May;94(5):1623-9. Epub 2009 Feb 3.
    Common variation in the DIO2 gene predicts baseline psychological well-being and response to combination thyroxine plus triiodothyronine therapy in hypothyroid patients.
    Panicker V, Saravanan P, Vaidya B, Evans J, Hattersley AT, Frayling TM, Dayan CM.
    Henry Wellcome Laboratories for Integrative Neurosciences and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, United Kingdom.
    Animal studies suggest that up to 80% of intracellular T(3) in the brain is derived from circulating T(4) by local deiodination. We hypothesized that in patients on T(4) common variants in the deiodinase genes might influence baseline psychological well-being and any improvement on combined T(4)/T(3) without necessarily affecting serum thyroid hormone levels.
    We analyzed common variants in the three deiodinase genes vs. baseline psychological morbidity and response to T(4)/T(3) in 552 subjects on T(4) from the Weston Area T(4) T(3) Study (WATTS). Primary outcome was improvement in psychological well-being assessed by the General Health Questionnaire 12 (GHQ-12).
    The rarer CC genotype of the rs225014 polymorphism in the deiodinase 2 gene (DIO2) was present in 16% of the study population and was associated with worse baseline GHQ scores in patients on T(4) (CC vs. TT genotype: 14.1 vs. 12.8, P = 0.03). In addition, this genotype showed greater improvement on T(4)/T(3) therapy compared with T(4) only by 2.3 GHQ points at 3 months and 1.4 at 12 months (P = 0.03 for repeated measures ANOVA). This polymorphism had no impact on circulating thyroid hormone levels.
    Our results require replication but suggest that commonly inherited variation in the DIO2 gene is associated both with impaired baseline psychological well-being on T(4) and enhanced response to combination T(4)/T(3) therapy, but did not affect serum thyroid hormone levels.

    Resistant Hypothyroidism? Consider Adding Liothyronine
    By: BRUCE JANCIN, Internal Medicine News Digital Network

    Not rated yet. Be the first who rates this item! 
    Click the rating bar to rate this item.

    In a secondary analysis of a study involving 552 hypothyroid patients randomized to LT4 or LT4/LT3, the prevalence of Thr92Ala homozygosity was 16%, and psychological well being in patients with the deiodinase 2 polymorphism improved significantly more on combination therapy than with LT4 alone (J. Clin. Endocrinol. Metab. 2009;94:1623-9).

    The fact that the Thr92Ala polymorphism is present in only 16% of individuals on thyroid hormone therapy might explain why so many randomized trials of LT4 versus combination therapy were negative: With study populations of only 20-141 patients, the trials would have been underpowered to detect a significant difference in treatment effect. Unfortunately, genetic testing for deiodinase polymorphisms is not commercially available, the endocrinologist observed.

    When he does resort to combination therapy, Dr. McDermott prescribes it in an LT4:LT3 ratio of 10-14:1 to mimic normal thyroid secretion. He generally has patients take LT3 twice daily, with the second dose no later than about 6 p.m. so it doesn’t interfere with sleep. Once-daily slow-release formulations of LT3 are available in Europe and work very well. Several companies are interested in developing a slow-release LT3 for the United States, which would be a welcome development, according to Dr. McDermott.

    Another option, once all else has been tried and failed, is to switch to another brand of LT4, he continued. Some patients may have adverse reactions to the various dyes and fillers contained in LT4 pills. When this is a potential concern, levothyroxine sodium (Tirosint), approved by the Food and Drug Administration a couple of years ago, is an attractive option. The LT4 in Tirosint is contained in oil in a liquid gelcap with no dyes or fillers, differentiating it from all other brand name and generic products, Dr. McDermott noted.

    He emphasized the importance of avoiding overtreatment with LT4 in an attempt to improve quality of life in patients with residual symptoms despite a TSH of 0.5-2.0 mU/L. Subclinical hyperthyroidism as defined by a TSH below 0.1 mU/L has been shown to significantly increase the risk of hip and spine fractures, atrial fibrillation, and cardiovascular mortality.

    Dr. McDermott reported having no financial conflicts.



  1. This was a great article! I was on a lower dose medication that worked well for years and then around when I turned 50, it was like the bottom dropped out. It took awhile to find a good doctor that knew how to treat it properly. I had a lot of BS problems until my thyroid was optimized.

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  4. Thanks, Dr Calder

  5. Here is a recent study from the American Thyroid Association site that has another point of view -

    "The researchers report that 49% of the patients preferred desiccated thyroid extract, 19% preferred levothyroxine and 23% had no preference."

    And to quote the lead researcher of the study "“We now know that once-daily desiccated thyroid extract is a safe alternative treatment for patients with hypothyroidism who are not satisfied with levothyroxine treatment."

  6. I'd like to see where DTE is "listed as obsolete" by the FDA. I have done quite a lot of delving into the history of DTE and it turns out that because it is a medication that was in use long before the FDA came into being, it has never been through a "New Drug Application" (NDA). The FDA has been aiming to get all drugs through an NDA process, but that is an expensive and arduous process, that will likely only serve to raise the prices of some of these old drugs that are clearly useful for some patients.

    To my thinking, the best thyroid medication is the one that safely and effectively resolves the symptoms of an individual thinking.


Your comments and questions are appreciated. David Calder,MD